1. Field of the Invention
The present invention relates generally to an information recording and reproducing apparatus such as a video cassette tape recorder of a helical scan type, and more particularly to an information recording and reproducing apparatus in which an audio-visual digital signal and auxiliary information read out from a first recording medium is reproduced and the reproduced audio-visual digital signal and auxiliary information are recorded in a second recording medium for the dubbing of the audio-visual digital signal and auxiliary information.
2. Description of the Related Art
A video cassette tape recorder (VCR) of a helical scan type is conventionally known as a magnetic recording and reproducing apparatus. In this VCR, a visual signal and an audio signal are converted into an audio visual (AV) digital signal in which the visual signal and the audio signal are coded according to a moving picture experts group (MPEG), the AV digital signal is recorded in a cassette type magnetic tape through a rotational head while making a recording track inclined with respect to a moving direction (or a longitudinal direction) of the magnetic tape, and a control signal having a plurality of control pulses arranged in equal intervals is recorded in the magnetic tape through a fixed control head while making a control track extending along the moving direction of the magnetic tape. When the AV digital signal and the control signal are reproduced, the AV digital signal is readout from the inclined recording track of the magnetic tape through the rotational head, and the control signal is read out from the control track of the magnetic tape through the control head.
2.1. First Previously Proposed Art
In this VCR, the AV digital signal are recorded and reproduced by operating a known analog circuit. In this case, to record information indicating the leading position of the recorded AV digital signal, a duty ratio of a particular group of control pulses recorded in a particular position corresponding to the leading position of the recorded AV digital signal is changed from a first duty ratio to a second duty ratio. Therefore, when the particular group of control pulses recorded in the particular position at the second duty ratio is detected in the reproducing unit, the leading position of the recorded AV digital signal can be recognized, so that the AV digital signal can be immediately reproduced from its leading position.
2.2. Problems of First Previously Proposed Art to Be Solved by the Invention
However, when a digital signal recorded in a magnetic tape is reproduced in a reproducing VCR functioning as a reproducing unit and the reproduced digital signal is dubbed and recorded in another magnetic tape in a slave VCR functioning as a recording unit, because each of the VCRs has no digital interface, a particular group of control pulses (hereinafter, called an index signal) recorded in a control track at the second duty ratio cannot be transmitted to the slave VCR because the control pulses are an analog signal, or a private connection line for the transmission of the analog index signal is additionally required in addition to a main digital signal line for the AV digital signal. Therefore, in cases where the index signal cannot be transmitted to the slave VCR, the index signal cannot be recorded in the slave VCR. Also, in cases where the private connection line is additionally used, a connector is required for each VCR. As a result, a cost for manufacturing an information recording and reproducing apparatus composed of the reproducing VCR, the slave VCR and the main digital signal line is increased.
2.3. Second Previously Proposed Art
Also, an information recording and reproducing apparatus, in which a digital VCR for recording and reproducing a digital signal is arranged as a reproducing unit, an analog VCR with a digital interface for recording and reproducing an analog signal is arranged as a recording unit and a cable connecting the digital VCR and the analog VCR is arranged, is known. In this information recording and reproducing apparatus, an AV digital signal recorded in a first magnetic tape is reproduced in the digital VCR, the reproduced AV digital signal is transmitted to the analog VCR through the cable and the digital interface of the analog VCR, and the reproduced AV digital signal is recorded in a second magnetic tape by the analog VCR. In this case, the AV digital signal of the first magnetic tape is recorded in each of a plurality of recording tracks which are arranged in parallel to each other and are inclined with respect to a tape moving direction (or a longitudinal direction) of the first magnetic tape. As shown in FIG. 1, a format of each inclined track Ti is composed of a margin area A1, a first preamble area A2, a sub-code area A3 for recording a sub-code signal, a first post-amble area A4, an inter-block gap (IBG) area A5, a second preamble area A6, a main data area A7 for recording the AV digital signal, an error correcting code area A8, a second post-amble area A9, and a margin area A10, and each inclined track is composed of 356 synchronous blocks. The main data area A7 is composed of 306 synchronous blocks. Each synchronous block is composed of a synchronous signal area of 2 bytes for the reproduction of the synchronous block, an address information area of 3 bytes, a header storing area of 3 bytes for recording various information, a data recording area of 96 bytes, and a parity area of 8 bytes for the error correction of the information of the synchronous block. The areas of each synchronous block are arranged in time-sequence, and each synchronous block is 112 bytes.
Therefore, when the digital VCR is operated, not only the AV digital signal recorded in the area A7 is reproduced but also the sub-code signal recorded in the area A3 is reproduced.
The sub-code signal indicates information data relating to the AV digital signal. For example, tape recording elapsed time data, recording date data, a program number corresponding to the AV digital signal and time data of a leading position (or a starting position) of the AV digital signal are included in the sub-code signal. Therefore, a change of information indicated by the sub-code signal is synchronized with the leading position of the AV digital signal.
2.4. Problems of Second Previously Proposed Art to Be Solved by the Invention
However, even though the AV digital signal and the sub-code signal reproduced in the digital VCR are received in the analog VCR through the digital interface of the analog VCR, because any recording unit for recording the sub-code signal is not arranged in the analog VCR, the AV digital signal and the sub-code signal recorded in the first magnetic tape cannot be dubbed in the second magnetic tape.
Also, in cases where any detecting unit for detecting the sub-code signal is not arranged in the analog VCR, even though a control signal generated in the analog VCR is recorded in the second magnetic tape, information indicated by the subcode signal cannot be transferred to the control signal. Therefore, it is difficult to immediately detect the leading position of the AV digital signal reproduced from the dubbed magnetic tape.
A first object of the present invention is to provide, with due consideration to the drawbacks of such a conventional information recording and reproducing apparatus, an information recording and reproducing apparatus in which a digital signal such as a digital AV signal and an analog identification signal such as an analog index signal recorded in a recording medium are recorded in another recording medium without using any private transmission line for the analog identification signal.
A second object of the present invention is to provide an information recording and reproducing apparatus and an information recording and reproducing method in which information of a sub-code signal recorded in a first recording medium with an AV digital signal are substantially recorded in a second recording medium even though the sub-code signal is not recorded in the second recording medium.
The first object is achieved by the provision of an information recording and reproducing apparatus, in which a main digital information signal recorded in a first track of a first recording medium and an auxiliary signal recorded in a second track of the first recording medium are reproduced in a reproducing apparatus and the main digital information signal and the auxiliary signal reproduced by the reproducing apparatus are dubbed and recorded in a second recording medium in a recording apparatus, the reproducing apparatus comprising:
a main information signal reproducing device for reproducing the main digital information signal recorded in the first track of the first recording medium;
an auxiliary signal reproducing device for reproducing the auxiliary signal recorded in the second track of the first recording medium in synchronization with the reproduction of the main digital information signal in the main information signal reproducing device, the auxiliary signal being composed of a plurality of pulses arranged in series, a particular group of pulses in the auxiliary signal being set to a special duty ratio, and the other pulses of the auxiliary signal being set to an ordinary duty ratio;
an identification signal detecting device for detecting the particular group of pulses as an analog identification signal from the auxiliary signal reproduced by the auxiliary signal reproducing device;
an identification code preparing device for preparing an identification code corresponding to the analog identification signal in cases where the analog identification signal is detected by the identification signal detecting device; and
a packet preparing device for preparing a packet defined according to a prescribed serial interface to arrange the main digital information signal reproduced by the main information signal reproducing device and the identification code reproduced by the auxiliary signal reproducing device in the packet, and
the recording apparatus comprising:
a packet detecting device for detecting the packet transmitted from the packet preparing device;
a main information signal detecting device for detecting the main digital information signal from the packet detected by the packet detecting device;
a main information signal recording device for recording the main digital information signal detected by the main information signal detecting device in a first track of the second recording medium;
an identification code detecting device for detecting the identification code from the packet detected by the packet detecting device;
an auxiliary signal generating device for generating a recording auxiliary signal composed of a plurality of recording pulses arranged in series, the recording pulses being set to a recording ordinary duty ratio;
a pulse duty ratio adjusting device for detecting a particular group of recording pulses, in synchronization with the detection of the identification code in the identification code detecting device, from the recording auxiliary signal generated by the auxiliary signal generating device, and adjusting the recording ordinary duty ratio of the particular group of recording pulses to a recording specific duty ratio; and
an auxiliary signal recording device for recording the auxiliary signal, in which the particular group of recording pulses is set to the recording specific duty ratio by the pulse duty ratio adjusting device, in a second track of the second recording medium in synchronization with the recording of the main digital information signal in the main information signal recording device.
In the above configuration, the main digital information signal of the first recording medium is reproduced by the main information signal reproducing device. Also, the auxiliary signal of the first recording medium is reproduced by the auxiliary signal reproducing device in synchronization with the reproduction of the main digital information signal, and the particular group of pulses is detected from the auxiliary signal as an analog identification signal by the identification signal detecting device. The analog identification signal, for example, indicates a leading position of the main digital information signal.
Because the identification signal is analog and the main digital information signal is digital, the identification signal and the main digital information signal cannot be packed in the same packet defined according to a prescribed serial interface. Therefore, in cases where the analog identification signal is detected, an identification code corresponding to the analog identification signal is prepared by the identification code preparing device. Because the identification code is digital, the identification code and the main digital information signal are packed in the same packet defined according to a prescribed serial interface by the packet preparing device, and the packet is transmitted to the recording apparatus.
In the recording apparatus, the main digital information signal is detected from the packet by the main information signal detecting device, and the identification code is detected from the packet by the identification code detecting device. The main digital information signal is recorded in a first track of a second recording medium by the main information signal recording device. Also, a recording auxiliary signal, in which a series of recording pulses is set to a recording ordinary duty ratio, is generated by the auxiliary signal generating device, and a particular group of recording pulses is adjusted to a recording specific duty ratio by the pulse duty ratio adjusting device in synchronization with the detection of the identification code. Therefore, the recording auxiliary signal, which is the same as the auxiliary signal, is produced according to the identification code. The recording auxiliary signal is recorded in a second track of the second recording medium by the auxiliary signal recording device in synchronization with the recording of the main digital information signal.
Accordingly, because the main digital information signal and the recording auxiliary signal are recorded in the second recording medium in the same manner as the recording of the main digital information signal and the auxiliary signal in the first recording medium, even though the identification signal of the auxiliary signal is analog, the main digital information signal and the auxiliary signal can be substantially dubbed in the second recording medium through one transmission line without using any private transmission line for the analog identification signal.
The second object is achieved by the provision of an information recording and reproducing apparatus, comprising:
a main information signal reproducing device for reproducing a main digital information signal and a sub-code signal recorded in a first track of a first recording medium, preparing a packet defined according to a prescribed serial interface to arrange the main digital information signal and the sub-code signal in the packet, a change of information indicated by the sub-code signal corresponding to a change of information indicated by the main digital information signal;
a packet transmitting line for transmitting the packet in which the main digital information signal and the sub-code signal are arranged by the main information signal reproducing device;
a packet detecting device for detecting the packet transmitted from the main information signal reproducing device through the packet transmitting line;
a main information signal detecting device for detecting the main digital information signal from the packet detected by the packet detecting device;
a main information signal recording device for recording the main digital information signal detected by the main information signal detecting device in a first track of a second recording medium;
a sub-code signal detecting device for detecting the subcode signal from the packet detected by the packet detecting device and detecting the change of the information indicated by the sub-code signal;
an auxiliary signal generating device for generating an auxiliary signal composed of a plurality of pulses arranged in series, the pulses being set to an ordinary duty ratio;
a pulse duty ratio adjusting device for detecting a particular group of pulses, which is synchronized with the change of the information of the sub-code signal detected by the sub-code signal detecting device, from the auxiliary signal generated by the auxiliary signal generating device, and adjusting the ordinary duty ratio of the particular group of pulses to a specific duty ratio; and
an auxiliary signal recording device for recording the auxiliary signal, in which the particular group of pulses is set to the specific duty ratio by the pulse duty ratio adjusting device, in a second track of the second recording medium to make the particular group of pulses of the auxiliary signal correspond to the change of the information of the main digital information signal recorded in the first track of the second recording medium.
In the above configuration, a main digital information signal and a sub-code signal are recorded in a first track of a first recording medium, and a change of information indicated by the sub-code signal corresponding to a change of information indicated by the main digital information signal. The main digital information signal and the sub-code signal are reproduced by the main information signal reproducing device and are packed in a packet. The packet is transmitted to the packet detecting device through the packet transmitting line, and the packet is detected. Thereafter, the main digital information signal is detected from the packet by the main information signal detecting device and is recorded in a first track of a second recording medium by the main information signal recording device.
Also, the sub-code signal is detected from the packet by the sub-code signal detecting device, the change of the information indicated by the sub-code signal is detected, and a particular group of pulses synchronized with the change of the information of the sub-code signal is detected from an auxiliary signal generated by the auxiliary signal generating device. An ordinary duty ratio of the particular group of pulses of the auxiliary signal is adjusted to a specific duty ratio by the pulse duty ratio adjusting device, and the auxiliary signal is recorded in a second track of the second recording medium on condition that the particular group of pulses of the auxiliary signal corresponds to the change of the information of the main digital information signal recorded in the first track of the second recording medium.
Accordingly, though the sub-code signal is not recorded with the main digital information signal in the second recording medium, because the auxiliary signal having the information indicated by the sub-code signal is recorded in the second recording medium, information recorded in the first recording medium can be substantially dubbed in the second recording medium.
Also, because an analog circuit for generating an auxiliary signal composed of a plurality of pulses arranged in series, an analog circuit for adjusting a duty ratio of a particular group of pulses of the auxiliary signal and an analog circuit for recording the auxiliary signal in synchronization with the main digital information signal are conventionally used, the auxiliary signal generating device, the pulse duty ratio adjusting device and the auxiliary signal recording device can be easily prepared, so that the information recording and reproducing apparatus can be manufactured at a low cost.
Also, because an analog circuit for reading out an auxiliary signal from the first recording medium is not required, the main information signal reproducing device can be easily realized by using a conventional reproducing apparatus, so that the information recording and reproducing apparatus can be manufactured at a low cost.
Also, because the sub-code signal is not recorded in the second recording medium, any device for recording the sub-code signal is not required.
The second object is also achieved by the provision of an information recording and reproducing method, comprising the steps of:
reproducing a main digital information signal and a subcode signal recorded in a first track of a first recording medium, a change of information indicated by the sub-code signal indicating a change of information indicated by the main digital information signal;
preparing a packet defined according to a prescribed serial interface to arrange the main digital information signal and the sub-code signal in the packet;
transmitting the packet through a packet transmitting line;
detecting the packet transmitted through the packet transmitting line;
detecting the main digital information signal from the packet;
detecting the sub-code signal from the packet;
detecting the change of the information indicated by the sub-code signal;
preparing an analog identification signal when the change of the information indicated by the sub-code signal is detected;
recording the main digital information signal in a first track of a second recording medium; and
recording the analog identification signal in a second track of the second recording medium to make the analog identification signal correspond to the change of information indicated by the main digital information signal.
In the above steps, because the analog identification signal is prepared when the change of the information indicated by the sub-code signal is detected, the analog identification signal is recorded in the second track of the second recording medium while the analog identification signal corresponds to the change of information indicated by the main digital information signal.
Accordingly, information recorded in the first recording medium can be substantially dubbed in the second recording medium.